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vol. 51
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issue 3
851-856
EN
A tumour therapy is proposed based on attenuated Salmonella typhimurium VNP20047 expressing the Escherichia coli cytosine deaminase gene. VNP20047 was administered intravenously to B16(F10) melanoma-bearing C57BL/6 mice. VNP20047 proliferated within tumours and livers regardless of the initial inoculum dose. After 10 days the number of bacteria increased in livers up to 4.2 × 106 cfu/g and decreased in tumours down to 5.9 × 106 cfu/g. VNP20047 at 1 × 105 cfu/mouse, when combined with 5-fluorocytosine, inhibited tumour growth by 85% without prolonging animal survival. Histology studies revealed severe lesions in tumours and livers. These data suggest that S. typhimurium VNP20047 induced inflammatory responses, even though the strain was attenuated.
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2006
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vol. 53
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issue 1
199-202
EN
Angiogenesis, i.e. formation of new blood vessels out of pre-existing capillaries, is essential to the development of tumour vasculature. The discovery of specific antiangiogenic inhibitors has important therapeutic implications for the development of novel cancer treatments. Vasostatin, the N-terminal domain of calreticulin, is a potent endogenous inhibitor of angiogenesis and tumour growth. In our study, using B16(F10) murine melanoma model and electroporation we attempted intramuscular transfer of human vasostatin gene. The gene therapy was combined with antiangiogenic drug dosing schedule of a known chemotherapeutic (cyclophosphamide). The combination of vasostatin gene therapy and cyclophosphamide administration improved therapeutic effects in melanoma tumours. We observed both significant inhibition of tumour growth and extended survival of treated mice. To our knowledge, this is one of the first reports showing antitumour efficacy of electroporation-mediated vasostatin gene therapy combined with antiangiogenic chemotherapy.
EN
Growth of tumors is strongly dependent upon supply of nutrients and oxygen by de novo formed blood vessels. Inhibiting angiogenesis suppresses growth of primary tumors as well and affects development of metastases. We demonstrate that recombinant MBP/vasostatin fusion protein inhibits proliferation of endothelial cells in vitro. The therapeutic usefulness of such intratumorally delivered recombinant protein was then assessed by investigating its ability to inhibit growth of experimental murine melanomas. In the model of B16-F10 melanoma the MBP/vasostatin construct significantly delayed tumor growth and prolonged survival of treated mice. A combination therapy involving MBP/vasostatin construct and cyclophosphamide was even more effective and led to further inhibition of the tumor growth and extended survival. We show that such combination might be useful in the clinical setting, especially to treat tumors which have already formed microvessel networks.
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In vivo gene transfer using cetylated polyethylenimine.

61%
EN
This report describes gene transfer in vitro as well as in vivo using cetylated low-molecular mass (600 Da) polyethylenimine (28% of amine groups substituted with cetyl moieties), termed CT-PEI. This compound is hydrophobic and has to be incorporated into liposomes in order to be suitable for gene transfer studies. Serum-induced plasmid DNA degradation assay demonstrated that CT-PEI-containing liposomal carriers could protect complexed DNA (probably via condensation). In vitro luciferase gene expression achieved using medium supplemented with 10% serum was comparable to that achieved in serum-reduced medium and was highest for CT-PEI/cholesterol liposomes, followed by CT-PEI/dioleoylphosphatidylcholine liposomes and PEI 600 Da (uncetylated) carrier. In vivo systemic transfer into mice was most efficient when liposome formulations contained CT-PEI and cholesterol. Higher luciferase expression was then observed in lungs than in liver. In conclusion: liposomes containing cetylated polyethylenimine and cholesterol are a suitable vehicle for investigating systemic plasmid DNA transfer into lungs.
EN
One of the preconditions of effective anticancer therapy is efficient transfer of the therapeutic agent (chemotherapeutic) to tumor cells. Fundamental barriers making drug delivery and action difficult include underoxygenation, elevated interstitial pressure, poor and abnormal tumor blood vascular network and acidic tumor milieu. In this study we aimed at developing an optimized scheme of administering a combination of an angiogenesis-inhibiting drug (vasostatin) and a chemotherapeutic (cyclophosphamide) in the therapeutic treatment of mice bearing experimental B16-F10 melanoma tumors. We report that the strongest tumor growth inhibition was observed in mice that received two, three or four vasostatin doses in combination with one injection of cyclophosphamide (i.e., V2 + CTX, V3 + CTX or V4 + CTX schemes). Double administration of vasostatin increases oxygenation of B16-F10 tumors. On the other hand, its five-fold administration lowers tumor oxygenation, breaks down tumor vascular network (increasing hypoxia) and leads in consequence to death of cancer cells and appearance of necrotic areas in the tumor. A decreased cyclophosphamide dose in combination with two doses of vasostatin (V2 + CTX scheme) inhibits tumor growth similarly to a larger dose of cyclophosphamide alone.
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